Injection molding is a molding technique suitable for molding small to large objects. A mold is generated in dedicated injection molding machines comprising a rotating screw in a barrel. The mold is injected continuously or with a mold buffer by means of pressure.
If the injectable object is large and complicated in shape, the pressure has to be very high in order to completely fill the cavity. Often several hot runners are used to overcome the high pressure level and to generate an even temperature profile while injecting polyethylene, in order to minimize the warpage of the injected large, hollow objects.
Examples of polyethylene for injection molding, particularly suited for preparing screw closures, are disclosed in WIPO Pat. App. Pub. No. WO2005103096.